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| Titel |
The parameterization of the general raindrop size distribution by the gamma probability density function |
| VerfasserIn |
Nan Yu, Pieter Hazenberg, Guy Delrieu, Brice Boudevillain, Remko Uijlenhoet |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250056532
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| Zusammenfassung |
| The raindrop size distribution (DSD) is crucial for understanding the relationships which link
the radar reflectivity factor to rainfall rate. In this study, we propose a dimensionless gamma
probability density function (pdf ) with two parameters to model the general distribution of
the DSD. A relationship between two parameters in the gamma pdf is derived based on
self-consistency. As a result, only one shape parameter, called μ, is necessary to describe the
variability of the general distribution. For each DSD spectrum, we apply a new method,
which uses the ratio of consecutive moments to estimate μ. For the whole DSD time series
data, with a global value of μ, this gamma pdf model can be easily adapted to both
the one- and two-moment normalisation approach presented in the literature. Our
theory has been implemented for a four-month DSD time series observed in the
Cévennes region, France. Results show the gamma pdf and its self-consistency
to be a good approximation to the observed general distribution. The uncertainty
in the moment estimations (e.g. the Z-R relationship) is partly explained by the
variability of the general distribution. Thus, a classification of the DSD spectra
by μ can improve the quality of moment estimation. Further research is needed
to investigate the physical meaning of the variability of the general distribution. |
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